From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: John Allen <john.allen@amd.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com,
rkrcmar@redhat.com, John Allen <john.allen@amd.com>
Subject: Re: [PATCH] kvm/svm: PKU not currently supported
Date: Thu, 19 Dec 2019 20:09:57 +0100 [thread overview]
Message-ID: <87immc873u.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20191219152332.28857-1-john.allen@amd.com>
John Allen <john.allen@amd.com> writes:
> Current SVM implementation does not have support for handling PKU. Guests
> running on a host with future AMD cpus that support the feature will read
> garbage from the PKRU register and will hit segmentation faults on boot as
> memory is getting marked as protected that should not be. Ensure that cpuid
> from SVM does not advertise the feature.
>
> Signed-off-by: John Allen <john.allen@amd.com>
> ---
> arch/x86/kvm/svm.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 122d4ce3b1ab..f911aa1b41c8 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5933,6 +5933,8 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
> if (avic)
> entry->ecx &= ~bit(X86_FEATURE_X2APIC);
> break;
> + case 0x7:
> + entry->ecx &= ~bit(X86_FEATURE_PKU);
Would it make more sense to introduce kvm_x86_ops->pku_supported() (and
return false for SVM and boot_cpu_has(X86_FEATURE_PKU) for vmx) so we
don't set the bit in the first place?
> case 0x80000001:
> if (nested)
> entry->ecx |= (1 << 2); /* Set SVM bit */
--
Vitaly
next prev parent reply other threads:[~2019-12-19 19:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 15:23 [PATCH] kvm/svm: PKU not currently supported John Allen
2019-12-19 19:09 ` Vitaly Kuznetsov [this message]
2019-12-19 19:49 ` John Allen
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